Features of near gravitational material tracers in a dense medium cyclone from PEPT

Abstract

Dense media cyclones are an integral part of circuits employed for coal processing, iron ore beneficiation, and recovery of diamonds. Many techniques have been applied in studying the separation performance of these devices including the use of different density tracers to develop density partition curves. This study focusses on tracking of near-gravity material radioactive tracers using the positron emission particle tracking technology. This near-gravity phase of coal has long been thought to cause separation inefficiencies which makes coal processing difficult. In this work, a slurry containing magnetite-based dense medium, and coal is pumped through a 100 mm Multotec cyclone. By means of the PEPT camera – apparatus with spatial and temporal resolutions of 1 mm and 1 ms respectively – and direct-adsorption-activated coal tracer particles within the medium, particle trajectories are recorded in space and time. The free vortex region is captured and shown to fit the Rankine vortex behaviour with n = 0.60 ± 0.08 overall for the free vortex power law decay. A logarithmic axial velocity model which captures the observed radial gradient around the locus of zero axial velocity is proposed. Radial profiles of turbulence intensity for the near gravitational material as captured by PEPT are presented. • labeled coal NGM particle trajectory in 4in operating DMC imaged using PEPT • resolve axial variability of two-vortex model at cyclone boundary transition • locus of zero vertical velocity captured • quantified turbulence distribution of NGM particle trajectories • demonstrate axial velocity model fit